Peptide and nucleotide can serve as best therapeutic but their uses are limited due to non-permeability to cell membrane barrier, which is highly specific. The delivery of protein to the mammalian cells is difficult due to lack of efficient delivery system. The protein transduction domains (PTDs) are the short stretch of amino acids, which can cross the cell membrane and have been tried by binding covalently to the protein to be targeted to the cells, which can be internalized independent of transporter or receptor. The most widely used PTDs for delivery of protein are from Drosophila, the Herpes Simplex Virus structural protein VP22 (Elliot and o'Hare 1997) and Human Immunodeficiency Virus-1 transcription activator T at protein (Frankel and Pabo, 1998). But the main disadvantage of this technology is that it needs covalent coupling of target protein with PTDs or expressing as fusion protein (Schwarze et al., 1999). This increases the additional steps and delays the start of actual experiment. Recent attention has been diverted to develop peptide, which can target the protein or nucleic acids, by noncovalent binding. Therefore, the objective of the present invention was to develop peptide vector, which can deliver both proteins and nucleic acid to variety of cells by exploiting the potential novel nuclear localization signal and a hydrophobic domain from IBDV, with minimal cytotoxicity.
To overcome the above said drawbacks, the present invention is an endeavor to development of a peptide as transfection system for both protein and nucleic acid for non-viral delivery. Although viral vectors remain most efficient gene transfer system in eukaryotic cells, safety concerns regarding their uses in humans and animals has increased the significance for development of non-viral delivery system. Furthermore, non-viral delivery has several advantages over viral systems as simple to use, noninfectious, easy to produce, do not induce specific immune responses and less cytotoxicity. The Applicant has identified for the first time a novel nuclear localization signal (NLS) from Infectious bursal disease virus and it was found to translocate to nucleus, independent of endocytosis, which is an essential feature to develop new successful delivery system. The vector peptide designed using this NLS was found to possess targeting ability of protein to cytoplasm and DNA to nucleus with high transfection ability and minimal cytotoxicity at much higher concentration than required for transfection. This new transfection reagent further has high transfection ability for production of recombinant antigens and direct proteins delivery. Moreover, this single reagent can transfect both protein and nucleic acid with low cost of production.